[LLDB] Initial version of PPC64 InstEmulation

Summary: Supports common prologue/epilogue instructions.

Reviewers: clayborg, labath

Reviewed By: clayborg, labath

Subscribers: davide, anajuliapc, alexandreyy, lbianc, nemanjai, mgorny, kbarton

Differential Revision: https://reviews.llvm.org/D43345
Author: Leandro Lupori <leandro.lupori@gmail.com>

llvm-svn: 326224